Locking fasteners are generally known and made of conventional metals, such as aluminum, brass, copper and steel, e.g., case hardened steel, as well as 316, 316L and 410 stainless steel. These conventional metals and alloys deform via the formation of dislocations, i.e., plastic work. For these conventional metals, the fabrication processes can mostly be placed into two categories—forming and cutting. Forming processes are those in which the applied force causes the material to plastically deform, but not to fail. Such processes are able to bend or stretch the metal into a desired shape. Cutting processes are those in which the applied force causes the material to fail and separate, allowing the material to be cut or removed. While the currently available fasteners are effective, an ever continuing need exists for tamper resistant fasteners, particularly for electronic devices.
Tampering involves the deliberate altering or breaking open a product, package, or system. Tamper resistance is resistance to tampering by either the normal users of a product, package, or system or others with physical access to it. There are many reasons for employing tamper resistance. Tamper resistance ranges from simple features like screws with special heads, more complex devices that render themselves inoperable or encrypt all data transmissions between individual chips, or use of materials needing special tools and knowledge. Tamper-resistant devices or features are common on packages to deter package or product tampering. In some applications, devices are only tamper-evident rather than tamper-resistant.
It has been argued that it is very difficult to make simple fasteners, particularly for electronic devices, to secure against tampering, because numerous types of attacks are possible. Yet, there is a need for a simple, but effective, tamper resistant fastener that would at least obviate physical tampering or make the fastener, and possibly the device to which the fastener is attached, non-functional if the fastener has been tampered with.